Module 3 Part 4 : Ray Model of Light Flashcards
what is the law of reflection
angle of incidence(i) = angle of reflection(r)
why does light bend when it goes through a medium
refraction
what is refraction
the bending of light as it moves between media of different densities
how does density effect the direction of light
it changes the lights speed, which causes the light to change direction
what happens when a light ray moves through a more dense medium
bends away from the normal
what happens when a light ray moves through a less dense medium
bends towards the normal
what happens when the light enters along the normal
the light will not refract
what is the normal
the normal is a line that is 90 degrees to a surface
what is Snell’s law (2)
As light enters a more dense medium the wavelength and velocity decrease
Frequency remains the same (colour is the same)
what is the equation of Snell’s law
n₁ sinθ₁ = n₂ sinθ₂
what is the symbol for refractive index
n
what is θ₁ in Snell’s law
the angle of incidence
what is θ₂ in Snell’s law
the angle of refraction
what is the equation to find the refractive index
n = c/vₙ
what is c in the refractive index equation
speed of light
what is vₙ in the refractive index equation
speed of light in the medium
what unit is refractive index measured in
it has no unit
how is total internal reflection achieved
when the light ray angle of incidence is above the critical angle of the light
what is the critical angle
the angle of incidence that provides an angle of refraction of 90-degrees.
what is the symbol for critical angle
θ𝒸
what is the critical angle formula
sinθ𝒸 = n₂/n₁
what type of lenses are there (2)
concave
convex
what happens when beams of light go through a convex lens
all beams go through the focal point
what happens when beams of light go through a concave lens
they bend out so that there origin is the focal point
what are the rules when locating an image formed by a convex lens (3)
A ray parallel with the optical axis passes through the focus
A ray that passes through the centre of the lens does not bend
A ray which passes through the focus will bend to be parallel
how are images characterised (3)
real or fake
inverted or not inverted
reduced or enlarged
what are the rules for finding an image in a mirror
A ray parallel to the principal axis will reflect through the focus
A ray passing through the centre of curvature of the mirror will reflect back along itself
A ray striking the centre of the mirror will reflect to make a symmetrical line in a “V” shape
A ray passing through the focus is reflected parallel to the principal axis
what are the equations of the inverse square law
I₁r₁² = I₂r₂²
